Is it even worth it to put alot into a 305 Tbi or should i just wait until it dies and get a 350?

 

It's entirely up to you, and what you want to get out of your car.
A 305 will net you better mileage but less power vs an equal spec'd 350.

The difference is not that much, but some guys hate the 305 with a passion.
Make no mistake though, you can make BIG power with either a 305 or a 350. Just look at fast355, he's built several VERY powerful engines, 305's and 350's. All you need is research and careful part selection.

 

This is how my latest 305 runs. Started out as a 305 vortec, has ported 305 heads, and a production LT4 cam.

 

If having a 350 isn't against your religion..........then you can just buy bolt on's that will swap over to your 350 when the time comes. Start with full exhaust then move to chip burning and finish up with an intake and TB.

By the time you get all those mods done you'll be ready to rebuild your 350 and swap in better heads and a cam all at the same time.